An understanding of interactions between membrane active biomolecules, test agents and surfactants on model lipid bilayer membranes is needed for many purposes, including, for example, for drug design and for developing an understanding of complex interactions in native biological membranes. The effects of detergents like Triton X-100, sodium dodecylsulfate, and octyl glucoside on phospholipid membranes have been studied widely. Detergents solubilize the membrane by forming detergent-lipid mixed micelles. Some membrane binding biomolecules also appear to affect the integrity and functionality of cell membranes. For example, biomolecules can disrupt membranes either by forming channels or pores through the lipid bilayer, or by complete solubilization.
Membrane active proteins such as α-toxin, α-hemolysin, streptolysin-O, tetanus toxin and membrane active peptides such as anti microbial peptides (AMP) (e.g., alameticin, nagainin, melittin and gamicidin) are few of the biomolecules that are known to disrupt lipid membranes.
Most disruption studies utilizing model membrane systems have used lipid vesicles or supported lipid membranes (SLM) on flat surfaces. In such studies, the disruption is mainly analyzed by monitoring the release of trapped compounds (mainly from vesicles) or by monitoring the change in physical properties (vesicles and SLM). However, lipid vesicles are instable and difficult. Supported lipid membranes on flat surfaces tend to be more robust than lipid vesicles and also allow spectroscopic analysis of the membranes. The instability and poorly defined structures of lipid vesicles limit their utility and essentially preclude their use in miniaturized technologies such as microfluidics. Disruption studies on supported lipid membranes on flat surfaces also have limited use for sensitive technologies such as fluorescence microscopy. Thus, lipid vesicles and supported lipid membranes on flat surfaces cannot readily be used in applications such as microfluidics. Part of the problem with lipid vesicles and supported lipid membranes on flat surfaces is due to the difficulties faced when trying to integrate these membranes into analytical and other devices.
Thus, new model membrane systems and methods for analyzing membrane structure are needed. Such membranes and methods can be used in clinical, environmental, and bioanalytical applications.